20-50 in most of america. 10-40 in wisconsin south dakota type places.
15-40 diesel oil is good for places with a normal winter.
15 50 full synthetic
that first number is indeed the coldest temperature the oil can see. ideally the 2nd number is 50.
so if it goes to 0 you actually need 0-40. So like I said, most of the us its never below 20 ever so 20 50 is what you want.
mobil 1 had an ad using the m20 in a 325 where it went a million miles with mobil 1 15 50.
absolutely do not use 5 30 in a m20 engine. in an m42 engine it would work but you will burn out a quart a day.
So I felt moved to post because dulbass monster said everything wrong.
also look for oil that has 1200 ppm of the additive zddp, an aditive that our old cars need but has been removed from modern oil for pollution.
its never on a bottle you have to look it up.
I go for full synthetic if its on sale.... Ive only changed it twice so thats all I know.
20 50 is gonna burn the least and leak the least so thats what Id shoot for first.
as far as transmission oil that was super dangerous advice.
there are 3 versions of the getrag 260, and the difference is the metal the synchronizers use.
each has a tag, look it up.
One needs synthetic oil 75 90 works. it has no tag.
one has a red tag, and it takes atf ( which is like a 10 40 )
one has a green tag, and take regular 80 w.
The synthetic works in the green tag one, but not in the red tag one and vice versa.
I personally used redline mt 90 on mine but royal purple might be similar. Im sure the orignal stuff was mobil 1 75 90w that was the corporate partner then.
Last edited by stamar; 03-22-2012 at 05:56 AM.